[lld][Darwin] Add support for the -sectcreate option.

llvm-svn: 251183

lld/include/lld/Core/DefinedAtom.h

@@ -151,6 +151,7 @@ public:
     typeNoAlloc,            // Identifies non allocatable sections [ELF]
     typeGroupComdat,        // Identifies a section group [ELF, COFF]
     typeGnuLinkOnce,        // Identifies a gnu.linkonce section [ELF]
+    typeSectCreate,         // Created via the -sectcreate option [Darwin]
   };
 
   // Permission bits for atoms and segments. The order of these values are

lld/include/lld/ReaderWriter/MachOLinkingContext.h

@@ -27,6 +27,7 @@ namespace mach_o {
 class ArchHandler;
 class MachODylibFile;
 class MachOFile;
+class SectCreateFile;
 }
 
 class MachOLinkingContext : public LinkingContext {
@@ -272,6 +273,10 @@ public:
   /// Add section alignment constraint on final layout.
   void addSectionAlignment(StringRef seg, StringRef sect, uint16_t align);
 
+  /// \brief Add a section based on a command-line sectcreate option.
+  void addSectCreateSection(StringRef seg, StringRef sect,
+                            std::unique_ptr<MemoryBuffer> content);
+
   /// Returns true if specified section had alignment constraints.
   bool sectionAligned(StringRef seg, StringRef sect, uint16_t &align) const;
 
@@ -416,6 +421,7 @@ private:
   llvm::StringMap<std::vector<OrderFileNode>> _orderFiles;
   unsigned _orderFileEntries;
   File *_flatNamespaceFile;
+  mach_o::SectCreateFile *_sectCreateFile = nullptr;
 };
 
 } // end namespace lld

lld/lib/Core/DefinedAtom.cpp

@@ -76,6 +76,7 @@ DefinedAtom::ContentPermissions DefinedAtom::permissions(ContentType type) {
   case typeGnuLinkOnce:
   case typeUnknown:
   case typeTempLTO:
+  case typeSectCreate:
     return permUnknown;
   }
   llvm_unreachable("unknown content type");

lld/lib/Driver/DarwinLdDriver.cpp

@@ -822,7 +822,7 @@ bool DarwinLdDriver::parse(llvm::ArrayRef<const char *> args,
     }
   }
 
-  // Handle input files
+  // Handle input files and sectcreate.
   for (auto &arg : parsedArgs) {
     bool upward;
     ErrorOr<StringRef> resolvedPath = StringRef();
@@ -876,6 +876,22 @@ bool DarwinLdDriver::parse(llvm::ArrayRef<const char *> args,
         return false;
       }
       break;
+    case OPT_sectcreate: {
+        const char* seg  = arg->getValue(0);
+        const char* sect = arg->getValue(1);
+        const char* fileName = arg->getValue(2);
+
+        ErrorOr<std::unique_ptr<MemoryBuffer>> contentOrErr =
+          MemoryBuffer::getFile(fileName);
+
+        if (!contentOrErr) {
+          diagnostics << "error: can't open -sectcreate file " << fileName << "\n";
+          return false;
+        }
+
+        ctx.addSectCreateSection(seg, sect, std::move(*contentOrErr));
+      }
+      break;
     }
   }
 

lld/lib/Driver/DarwinLdOptions.td

@@ -177,7 +177,10 @@ def arch : Separate<["-"], "arch">,
      HelpText<"Architecture to link">;
 def sectalign : MultiArg<["-"], "sectalign", 3>,
      MetaVarName<"<segname> <sectname> <alignment>">,
-     HelpText<"alignment for segment/section">;
+     HelpText<"Alignment for segment/section">;
+def sectcreate : MultiArg<["-"], "sectcreate", 3>,
+     MetaVarName<"<segname> <sectname> <file>">,
+     HelpText<"Create section <segname>/<sectname> from contents of <file>">;
 def image_base : Separate<["-"], "image_base">;
 def seg1addr : Separate<["-"], "seg1addr">, Alias<image_base>;
 def demangle : Flag<["-"], "demangle">,

lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp

@@ -13,6 +13,7 @@
 #include "FlatNamespaceFile.h"
 #include "MachONormalizedFile.h"
 #include "MachOPasses.h"
+#include "SectCreateFile.h"
 #include "lld/Core/ArchiveLibraryFile.h"
 #include "lld/Core/PassManager.h"
 #include "lld/Core/Reader.h"
@@ -749,6 +750,20 @@ void MachOLinkingContext::addSectionAlignment(StringRef seg, StringRef sect,
   _sectAligns.push_back(entry);
 }
 
+void MachOLinkingContext::addSectCreateSection(
+                                        StringRef seg, StringRef sect,
+                                        std::unique_ptr<MemoryBuffer> content) {
+
+  if (!_sectCreateFile) {
+    auto sectCreateFile = llvm::make_unique<mach_o::SectCreateFile>();
+    _sectCreateFile = sectCreateFile.get();
+    getNodes().push_back(llvm::make_unique<FileNode>(std::move(sectCreateFile)));
+  }
+
+  assert(_sectCreateFile && "sectcreate file does not exist.");
+  _sectCreateFile->addSection(seg, sect, std::move(content));
+}
+
 bool MachOLinkingContext::sectionAligned(StringRef seg, StringRef sect,
                                          uint16_t &align) const {
   for (const SectionAlign &entry : _sectAligns) {

lld/lib/ReaderWriter/MachO/SectCreateFile.h

@@ -0,0 +1,94 @@
+//===---- lib/ReaderWriter/MachO/SectCreateFile.h ---------------*- c++ -*-===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H
+#define LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H
+
+#include "lld/Core/DefinedAtom.h"
+#include "lld/Core/Simple.h"
+#include "lld/ReaderWriter/MachOLinkingContext.h"
+
+namespace lld {
+namespace mach_o {
+
+//
+// A FlateNamespaceFile instance may be added as a resolution source of last
+// resort, depending on how -flat_namespace and -undefined are set.
+//
+class SectCreateFile : public File {
+public:
+
+  class SectCreateAtom : public SimpleDefinedAtom {
+  public:
+    SectCreateAtom(const File &file, StringRef segName, StringRef sectName,
+                   std::unique_ptr<MemoryBuffer> content)
+      : SimpleDefinedAtom(file),
+        _combinedName((segName + "/" + sectName).str()),
+        _content(std::move(content)) {}
+
+    uint64_t size() const override { return _content->getBufferSize(); }
+
+    Scope scope() const override { return scopeGlobal; }
+
+    ContentType contentType() const override { return typeSectCreate; }
+
+    SectionChoice sectionChoice() const override { return sectionCustomRequired; }
+
+    StringRef customSectionName() const override { return _combinedName; }
+
+    DeadStripKind deadStrip() const override { return deadStripNever; }
+
+    ArrayRef<uint8_t> rawContent() const override {
+      const uint8_t *data =
+        reinterpret_cast<const uint8_t*>(_content->getBufferStart());
+      return ArrayRef<uint8_t>(data, _content->getBufferSize());
+    }
+
+    StringRef segmentName() const { return _segName; }
+    StringRef sectionName() const { return _sectName; }
+
+  private:
+    std::string _combinedName;
+    StringRef _segName;
+    StringRef _sectName;
+    std::unique_ptr<MemoryBuffer> _content;
+  };
+
+  SectCreateFile() : File("sectcreate", kindObject) {}
+
+  void addSection(StringRef seg, StringRef sect,
+                  std::unique_ptr<MemoryBuffer> content) {
+    _definedAtoms.push_back(
+      new (allocator()) SectCreateAtom(*this, seg, sect, std::move(content)));
+  }
+
+  const AtomVector<DefinedAtom> &defined() const {
+    return _definedAtoms;
+  }
+
+  const AtomVector<UndefinedAtom> &undefined() const {
+    return _noUndefinedAtoms;
+  }
+
+  const AtomVector<SharedLibraryAtom> &sharedLibrary() const {
+    return _noSharedLibraryAtoms;
+  }
+
+  const AtomVector<AbsoluteAtom> &absolute() const {
+    return _noAbsoluteAtoms;
+  }
+
+private:
+  AtomVector<DefinedAtom> _definedAtoms;
+};
+
+} // namespace mach_o
+} // namespace lld
+
+#endif // LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H

lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp

@@ -437,6 +437,7 @@ template <> struct ScalarEnumerationTraits<lld::DefinedAtom::ContentType> {
     io.enumCase(value, "no-alloc",        DefinedAtom::typeNoAlloc);
     io.enumCase(value, "group-comdat", DefinedAtom::typeGroupComdat);
     io.enumCase(value, "gnu-linkonce", DefinedAtom::typeGnuLinkOnce);
+    io.enumCase(value, "sectcreate",      DefinedAtom::typeSectCreate);
   }
 };
 

lld/test/mach-o/Inputs/hw.raw_bytes

@@ -0,0 +1 @@
+hello

lld/test/mach-o/sectcreate.yaml

@@ -0,0 +1,12 @@
+# RUN: lld -flavor darwin -r -arch x86_64 -o %t -sectcreate __DATA __data \
+# RUN:   %p/Inputs/hw.raw_bytes -print_atoms | FileCheck %s
+
+# CHECK: --- !native
+# CHECK: path:            '<linker-internal>'
+# CHECK: defined-atoms:
+# CHECK:   - scope:           global
+# CHECK:     type:            sectcreate
+# CHECK:     content:         [ 68, 65, 6C, 6C, 6F, 0A ]
+# CHECK:     section-choice:  custom-required
+# CHECK:     section-name:    __DATA/__data
+# CHECK:     dead-strip:      never